Importance of mixing ratio for a long-term CO2 flux measurement with a closed-path system

Taro Nakai; Hiroki Iwata; Yoshinobu Harazono

doi:10.1111/j.1600-0889.2011.00538.x

Importance of mixing ratio for a long-term CO2 flux measurement with a closed-path system

Tellus B: Chemical and Physical Meteorology

Volume 63 (2011): Issue 3

By: Taro Nakai, Hiroki Iwata and Yoshinobu Harazono

Open Access

|Jan 2011

Abstract

The new type closed-path CO₂/H₂O infrared gas analyser enables us to calculate CO₂ fluxes from both the mixing ratio (FMR c ) and mass density of CO₂ (F^WPL _c ). After the WPL correction was applied, FMR c and F^WPL _c were almost in accord with each other. However, F^WPL _c tended to be slightly larger than FMR c , which resulted in a significant difference in cumulative CO₂ fluxes.We found that this difference was explained by the pressure covariance term, which is normally omitted in the WPL correction. Therefore, ignoring the pressure covariance term in the WPL correction can cause a serious error in estimation of annual net ecosystem exchange. To reduce uncertainties in calculations, we recommend using the mixing ratio for calculation of CO₂ fluxes when using the new type closed-path infrared gas analyser.

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Articles in this issue

DOI: https://doi.org/10.1111/j.1600-0889.2011.00538.x | Journal eISSN: 1600-0889

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Language: English

Page range: 302 - 308

Submitted on: Jan 21, 2011

Accepted on: Apr 14, 2011

Published on: Jan 1, 2011

Published by: Stockholm University Press

In partnership with: Paradigm Publishing Services

© 2011 Taro Nakai, Hiroki Iwata, Yoshinobu Harazono, published by Stockholm University Press
This work is licensed under the Creative Commons Attribution 4.0 License.

Volume 63 (2011): Issue 3